April 15, 2008

New Platform Provides Stroll Through Ancient Cities

Researchers in Europe have developed an omni-directional treadmill that lets users explore the ancient city of Pompeii.

The "motion platform" treadmill, called CyberCarpet, will be unveiled this week, and will give users the impression of taking a "Ënatural walk' in any direction.

Researchers combined the platform with a tracking system and virtual reality software recreating Pompeii. The scientists believe the technology could also be used for other applications such as gaming, education, architecture, disaster training and medical rehabilitation.

CyberCarpet is made up of several belts that form an endless plane along two axes. But the key to the system is a platform with a large chain drive made up of 25 conventional treadmills that move along a path at right angles to the direction the chain is moving.

The platform provides a walking area of 4.5m by 4.5m and is quick enough to allow jogging at a speed of two meters per second.

Omni-directional treadmills have been in development for many years by many, including the US military.

"This is the first omni-directional platform that allows near natural walking," Dr Marc Ernst, research group leader at Germany's Max Planck Institute for Biological Cybernetics, told BBC News.

The chain and belts operate independently such that the user is recentered on the platform if he or she accelerates from a point towards the edge of the platform.

Powered by a series of 40 kilowatt motors, the treadmill weighs 11 tons and can move a mass of up to 7 tons.

"The size of the platform matters," said Dr Ernst. "If you make it too small you have to counteract each step a person takes. It feels like walking on ice.

"You need some size and from a perceptual point of view the larger the better," he said, adding that the platform would have to be 100m by 100m if a walker were to have no sensation of being recentered

"To make it feel natural for walking you cannot go any smaller than six meters by six meters; it's a question of physics."

Dr Ernst said walking on the CyberCarpet "feels great".

"It feels relatively natural. You do feel the acceleration of the belts.

"But you don't need any harness - we wear them for safety in case someone was to fall. But no-one ever has."

The researchers combined the platform with virtual reality headsets to allow the impression of exploring 3D worlds. The scientists have been developing a tracking system that lets "walkers" forego the type of suits used in Hollywood films for motion capture. Instead, the system uses cameras that track the position and posture of the individual. That motion detection in turn controls the treadmill's speed and interactions with the 3D virtual world.

The team is working with the Swiss Federal Institute of Technology (ETHZ), which has developed a software package called CityEngine that rapidly creates large-scale virtual environments of cities, in varying degrees of detail.

During a conference in Germany this week, the teams will showcase CyberWalk and CityEngine to demonstrate how users can stroll around the ancient cities of Pompeii and Rome.

"Pompeii is a great showcase because it lets you discover a city that no longer exists," said Dr Ernst.

"We are using virtual reality to study human behavior. We want to learn how different sensory signals are used by the human brain to generate representation or layout of a location," he added.

"How do you create a mental layout of a town for the first time? We want to learn what information is used but also how you combine it.

"How do different sensory modalities interact?"

The platform was produced through collaborative efforts between the Swiss and German institutes, as well as the University of Rome, the Institute of Applied Mechanics and the Institute of Automatic Control Engineering, in Munich.